A number of operational systems depend on the alignment of two different measures to efficiently or safely produce desired results. Such operations generally require a human operator's expertise and continual evaluation of the two different variables, often viewed on different gauges involving different metrics, and relying on measurement, experience, or “feel,” to keep the system within operational parameters that yield the desired outcomes. Examples include chemical processes in which an exact and dynamic combination of heat and pressure is required to produce a specific compound, or aircraft flight operations in which an exact and dynamic combination of airspeed and angle-of-attack can mean the difference between a safe landing and loss of control. Such joint optimization situations involve coordinating the changing values of differently-measured variables, adjusting them together over a defined range, and keeping them within required bounds until target outcomes are achieved. Ordinarily, a significant effort is required to keep the operating variables aligned, and in some cases, failure to do so can result in a range of operating failures, including wasted product or even explosions in chemical environments; and accidents on takeoff and landing in flight.
Joint optimization problems extend to non-technical contexts as well. Wherever close coordination of two dimensions of a system is essential, the same requirements come into play. Investment portfolio management turns on optimizing risk and return across changing asset classes. Effective human resource management requires assessing whether employees are “meeting expectations.” Here, optimizing alignment between management's expectations and employee's desire for advancement creates a joint optimization setting just as compelling as any engineering challenge.